Control of follicular maturation in the pig and rhesus monkey is being investigated. Granulosa and thecal cells are removed from follicles at various stages and grown in cultures with various hormone and fractions of follicular fluid. Granulosa cell Lh/hCG receptor, cyclic AMP production and progesterone secretion are used as end points for the degree of maturation (leuteinization). Effects of in vivo injections of porcine follicular fluid in the rhesus monkey upon follicular growth and maturation and the ability of granulosa cells to leutinize are also being examined. Control of granulosa cell aromatization of androgen is also being examined in monkey and pig granulosa cell cultures.